Transmitter, signal transmitting method, data distributing system and its method, data receiver, data providing device and its method and data transmitter

ABSTRACT

To enable usage of content at a receiver which does not have a copying function even if copyright protection is provided. Model names of receivers not having a function enabling copying of content are held in an authentication processing circuit ( 151 ) of a transmitter ( 10 ). When a model name obtained from a connected receiver ( 40 ) is held, regardless of whether the content is copyright protected, a signal selection circuit ( 122 ) selects a terminal a side, a switch ( 123 ) is turned on, and an unencrypted signal is transmitted. When a change of the receiver ( 40 ) is detected by a hot plug detection function or a plug and play function at a processing circuit ( 152 ) during the transfer of a signal of copyright protected content without providing copyright protection, the selection circuit ( 122 ) is made to select a terminal b side or the switch ( 123 ) is turned off to suspend the transfer of the non-copyright protected signal. The information indicating the receiver is held in a tamper-proof updateable manner.

TECHNICAL FIELD

[0001] The present invention relates to a transmitter, signal transfermethod, data distribution system and method of same, data receiver, dataprovider and method of same, and data transferee. More specifically, thepresent invention relates to a technology for holding in advanceinformation indicating a receiver which does not have the function ofbeing able to copy content using a transferred content signal, andcontrolling the transfer of a content signal of content or a copyrightprotected content signal according to whether or not informationindicating a connected receiver is included in the held information atthe time of transfer of the content.

BACKGROUND ART

[0002] In the past, a computer system etc. has converted a digital imagesignal to an analog image signal and supplied the same to a displaydevice by analog transmission. However, along with the spread of displaydevices for driving displays by using a digital signal, for example,liquid crystal displays, the method of digitally transferring a digitalimage signal without converting the same to an analog signal forpreventing degradation of the quality of the image or reducing costs hasbeen standardized. For example, the DDWG (Digital Display Working Group)is formulating a DVI (Digital Visual Interface, Version 1.0)specification. This DVI specification uses a TMDS (transition minimizeddifferential signal) channel developed by Silicon Image Corp. of theU.S. to serially transfer a digital three-primary color image signal bythe baseband for every color.

[0003]FIG. 4 is a conceptual view of a signal transfer system fortransferring a digital image signal of content by using a channel of theDVI specification. A transmitter (for example a computer system or settop box) 20 for transmitting the image signal and a receiver (displaydevice, television system, etc.) 50 for receiving the image signal anddisplaying the image are connected via channels 30 of the DVIspecification. In a DVI specification channel, not only is a TMDSchannel for transferring a digital image signal used as mentioned above,but also a bi-directional channel (I²C bus or the like) used forinformation transfer in a DDC (display data channel) specificationrelating to plug and play established by VESA (Video ElectronicsStandard Association) is provided.

[0004] Here, if a transmission controller 25 of the transmitter 20detects that the receiver 50 has been connected, the transmissioncontroller 25 communicates with a reception controller 53 of thereceiver 50 according to the DDC protocol, controls an image signalgenerator 21 based on receiver information obtained from the receptioncontroller 53, for example, information of a model name and resolutionof the receiver 50, and generates a digital three-primary color imagesignal optimum for the receiver 50. The three-primary color image signalDG is supplied to a transmission processor 22 comprised by using a TMDStransmission circuit. The transmission processor 22 generates a basebandserial transfer signal SD from the supplied three-primary color imagesignal DG and supplies it to the receiver 50 from a connector 27 via thechannel 30. The receiver 50 supplies the serial transfer signal SDsupplied via a connector 51 to a reception processor 52. The receptionprocessor 52 is comprised by using a TMDS reception circuit andgenerates the digital three-primary color image signal DS from theserial transfer signal SD and supplies it to an image display 54. Forthis reason, the image display 54 can optimize and display an image ofthe content based on the three-primary color image signal DS.

[0005] Since the content transferred via the channel 30 of TMDS isconverted to the digital signal, a perfect copy can be prepared easilyand limitlessly. This is a great advantage for the user, but a problemin terms of protecting the rights of the side providing a movie or otherwork. For this reason, a proposal referred to as “DVI-CP (ContentProtection)” using encryption technology for copyright protection whentransferring a digital signal of content by using a DVI specificationchannel has been made by Intel Corporation of the U.S.

[0006]FIG. 5 is a conceptual view of a signal transfer system fortransferring a signal of content compatible with the DVI-CPspecification. The image signal generator 21 of a transmitter 20 a has aprotection information detector 23 connected to it. This protectioninformation detector 23 decides the digital three-primary color imagesignal DG to be transferred includes protection information indicatingthat the signal is one of content to be copyright protected. When thisprotection information detector 23 detects the protection information(when it is decided that the content is to be copyright protected), anencryption circuit 221 provided in a transmission processor 22 aencrypts the three-primary color image signal DG and provides thisencrypted signal, that is, the three-primary color image signal DGE, tothe TMDS signal circuit 222, to generate the serial transfer signal SD.

[0007] Also, a reception processor 52 a of a receiver 50 a is comprisedby using not only a TMDS reception circuit 521, but also a decryptioncircuit 522. The TMDS reception circuit 521 receives the serial transfersignal SD, generates a three-primary color image signal, and supplies itto the decryption circuit 522 for the decryption processing. Here, atransmission controller 25 a of the transmitter 20 a and a receptioncontroller 53 a of the receiver 50 a perform processing for mutualauthentication according to the DDC protocol and, when deciding that acorrect party is connected, supply the encryption key DC used for theencryption of the three-primary color image signal DG to the decryptioncircuit 522 to enable the decryption circuit 522 to correctly decryptthe encrypted three-primary color image signal. The digitalthree-primary color image signal DG obtained at this decryption circuit522 is supplied to the image display 54. Even if the three-primary colorimage signal DG is transferred encrypted, the image of content can becorrectly optimized and displayed on an image display 3.

[0008] Also, since the serial transfer signal SD is generated based onthe encrypted three-primary color image signal DGE, the unencryptedthree-primary color image signal DS cannot be obtained just by receivingthe serial transfer signal SD, so the content can be prevented frombeing digitally copied as it is.

[0009] If, however, encryption technology for copyright protection isadded to this DVI specification and becomes standard after use ofreceivers 50 based on the above DVI specification starts, when atransmitter 20 a based on the new specification encrypts and outputs adigital image signal, a prior DVI specification receiver 50 sometimeswill not be able to display the image since it does not have thefunction of decrypting an encrypted digital image signal.

[0010] For example, as shown in FIG. 6, when outputting a digital imagesignal from a transmitter 20 based on the conventional DVI specificationas a serial transfer signal SD, both a receiver 50 based on theconventional DVI specification or a receiver 50 a based on the newspecification including the encryption technology can display the imageof the content. Also, when outputting a digital image signal from atransmitter 20 a based on the new specification including the encryptiontechnology as the serial transfer signal SD, a receiver 50 a having thefunction of decrypting an encrypted digital image signal can display theimage of the content. Since the receiver 50 does not have a decryptionfunction however, sometimes the receiver 50 cannot be used for copyingcontent without inviting degradation of the quality of the image etc.,for example, it does not have the function of outputting the supplieddigital three-primary color image signal or converting the three-primarycolor image signal to for example an NTSC system video signal for outputand therefore cannot display the image of the content even if it isclear that copyright protection is possible.

DISCLOSURE OF THE INVENTION

[0011] An object of the present invention is to provide a transmitterand a signal transfer method enabling correct display of an image evenif a transmitter for a digital image signal designed for a digitaltransfer method incorporating encryption technology for copyrightprotection is connected with a receiver designed for a digital transfermethod not incorporating encryption technology for copyright protection.

[0012] Another object of the present invention is to provide a datadistribution system and a data distribution method enabling a contentowner to directly control copying as desired while using a standardapparatus as a processor after the receiver.

[0013] Still another object of the present invention is to provide adata receiver used in such a content distribution system, receiving thedistributed content data, performing adequate right processing, andoutputting the content data in a usable manner.

[0014] Still another object of the present invention is to provide adata provider and a data providing method for providing content data tobe distributed in a state where the owner of the content can control theusage thereof.

[0015] Still another object of the present invention is to provide adata transferer for transferring the data provided in this way.

[0016] Accordingly, a transmitter according to the present inventioncomprises a transmission processing means for transferring a contentsignal or processing copyright protection to a content signal and thentransferring the processed content signal and a transmission controllingmeans for holding information indicating a receiver which does not havea function enabling copying of content by using the content signal theprocessed content signal transferred from the transmission processingmeans and controlling output of the signal to be transferred from thetransmission processing means according to whether or not informationindicating the receiver which is connected to the transmissionprocessing means is included in the held information.

[0017] A signal transfer method according to the present inventionincludes the steps of holding in a transmitter information indicatingreceivers not having the function of being able to receive a contentsignal to copy the content and controlling the output of the contentsignal or content signal after provided with copyright protection at thetransmitter according to whether or not information indicating aconnected receiver is included in the held information.

[0018] In the present invention, when for example the model names ofreceivers not having the function of being able to use a transferredcontent signal to copy the content are held in a transmitter in advanceand the model name of a connected receiver is included in the held modelnames, a non-copyright protected content signal is transferred from thetransmitter to the receiver regardless of whether or not the content tobe transferred is copyright protected. Also, when a change of thereceiver is detected by a hot plug detection function or a plug and playfunction while transferring a content signal of copyright protectedcontent without providing copyright protection, the transfer of thenon-copyright protected content signal is suspended or a copyrightprotected content signal is transferred instead of the non-copyrightprotected content signal. Also, the transmitter holds the model name orother information indicating the receiver in a tamper-proof updateablemanner.

[0019] A data distribution system according to the present inventioncomprises a data providing means for adding first control informationfor controlling a usage state of the content data to the intendedcontent data and providing the result as the data to be distributed, adata transmitting means for performing predetermined second encryptionon the provided data to be distributed and transmitting the encrypteddata to be distributed, and a data receiving means for receiving thetransmitted encrypted data to be distributed, performing decryption ofthe second encryption, detecting the first control information from thedecrypted data to be distributed, and controlling the output of thecontent data based on the detected first control information.

[0020] Preferably, the data providing means superimposes the firstcontrol information as electronic watermark information on the contentdata and provides the superimposed content data as the data to bedistributed to the data transmitting means, the data transmitting meansperforms the predetermined second encryption on the provided data to bedistributed and transmits the encrypted data to be distributed, and thedata receiving means receives the transmitted encrypted data to bedistributed, performs the decryption of the second encryption, detectsthe superimposed first control information from the decrypted data to bedistributed, and controls the output of the content data based on thedetected first control information.

[0021] More preferably, the data providing means performs predeterminedfirst encryption on the content data with the first control informationsuperimposed thereon as the electronic watermark information andprovides the encrypted data as the data to be distributed to the datatransmitting means, the data transmitting means performs the secondencryption for the provided data to be distributed and transmits theencrypted data to be distributed, and the data receiving means receivesthe transmitted encrypted data to be distributed, performs thedecryption of the second encryption, generates the content data with theelectronic watermark information superimposed thereon by performing thedecryption of the first encryption, detects the superimposed firstcontrol information from the generated content data, and controls theoutput of the content data based on the detected information.

[0022] Specifically, the data transmitting means adds second controlinformation for controlling a usage state of the content data to theprovided data to be distributed, performs the second encryption on thedata to be distributed with the second control information addedthereto, and transmits the encrypted data to be distributed, the datareceiving means receives the transmitted encrypted data to bedistributed, performs the decryption of the second encryption, detectsthe second control information, generates the content data with theelectronic watermark information superimposed thereon by performing thedecryption of the first encryption for the decrypted data to bedistributed, detects the first control information superimposed as theelectronic watermark information from the generated content data, andcontrols the output of the content data based on the detected firstcontrol information and second control information.

[0023] More specifically, the data providing means adds a controldescriptor indicating the first control information to the content dataand provides the content data with the control descriptor added theretoas the data to be distributed to the data transmitting means, the datatransmitting means performs the predetermined second encryption for theprovided data to be distributed and transmits the encrypted data to bedistributed, and the data receiving means receives the transmittedencrypted data to be distributed, performs the decryption of the secondencryption, detects the added first control information from thedecrypted data to be distributed, and controls the output of the contentdata based on the detected first control information.

[0024] Preferably, the data transmitting means adds second controlinformation for controlling a usage state of the content data to theprovided data to be distributed, performs the second encryption for thedata to be distributed with the second control information addedthereto, and transmits the encrypted data to be distributed, and thedata receiving means receives the transmitted encrypted data to bedistributed, performs the decryption of the second encryption, detectsthe second information, performs the decryption of the first encryptionfor the decrypted data to be distributed to generate content data withthe control descriptor added thereto, detects the first controlinformation added as the control descriptor from the generated contentdata, and controls the output of the content data based on the detectedfirst control information and second control information.

[0025] Preferably, the data providing means superimposes third controlinformation for controlling a usage state of the signal when outputtingthe content data by an analog signal on the content data as theelectronic watermark information and provides the content data with thethird control information superimposed thereon as the data to bedistributed, the data transmitting means performs the predeterminedsecond encryption for the provided data to be distributed, transmits theencrypted data to be distributed, and the data receiving means receivesthe transmitted encrypted data to be distributed, performs thedecryption of the second encryption, and outputs the signal with thedecrypted the third control information superimposed thereon as theelectronic watermark information as the analog signal output in responseto a request.

[0026] Preferably, the data receiving means further has a memory meansfor storing information concerning charging with respect to a usage ofthe content data based on a usage state of the received content data.

[0027] A data distribution method according to the present inventioncomprises the steps of adding first control information for controllinga usage state of content data to intended content data based on aninstruction of an owner of the content data and providing the result asthe data to be distributed, performing predetermined second encryptionon the provided data to be distributed, transmitting the encrypted datato be distributed, receiving the transmitted encrypted data to bedistributed at any receiver, performing the decryption of the secondencryption, detecting the first control information from the decrypteddata to be distributed, and controlling the output of the content databased on the detected first control information.

[0028] A data receiver according to the present invention is a datareceiver for receiving a signal comprised of data to be distributedincluding intended content data plus first control information forcontrolling a usage state of the content data and transmitted afterperforming predetermined second encryption, comprising a receiving meansfor receiving the transmitted signal, a second decrypting means forperforming decryption of the second encryption with respect to thereceived signal, a first control information detecting means fordetecting the first control information from the decrypted data to bedistributed, and an output controlling means for controlling the outputof the content data based on the detected first control information.

[0029] A data provider according to the present invention has a controlinformation adding means for adding control information for controllinga usage state of content data designated by an owner of the content datato intended content data and provides the content data with the controlinformation added thereto as data to be distributed.

[0030] A data providing method according to the present inventioncomprises the steps of adding control information for controlling ausage state of content data designated by an owner of content data tointended content data, encrypting the content data with the controlinformation added thereto by a predetermined method, and providing theencrypted content data as the data to be distributed.

[0031] A data transferer according to the present invention comprises anencrypting means for further encrypting, by a predetermined method, datato be distributed including intended content data plus controlinformation for controlling a usage state of the content data designatedby an owner of the content data and encrypted by a predetermined schemeand a transferring means for transferring the encrypted data to bedistributed to any channel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0032] The above objects and features of the present invention willbecome more apparent from the following description given with referenceto the accompanying drawings, wherein:

[0033]FIG. 1 is a conceptual view of a signal transfer system accordingto the present invention,

[0034]FIG. 2 is a view of a pin arrangement of a connector of the DVIspecification,

[0035]FIG. 3 is a flowchart of an operation of a transmitter,

[0036]FIG. 4 is a conceptual view of a signal transfer system of the DVIspecification,

[0037]FIG. 5 is a conceptual view of a signal transfer system designedfor the DVI-CP specification,

[0038]FIG. 6 is a view of compatibility of hardware based on the DVIspecification and hardware based on the DVI-CP specification,

[0039]FIG. 7 is a view of an overall schematic configuration of acontent distribution system of a second embodiment of the presentinvention,

[0040]FIG. 8 is a view of the configuration of a principal part of afirst concrete example of the content distribution system shown in FIG.7,

[0041]FIG. 9 is a view of the configuration of a principal part of asecond concrete example of the content distribution system shown in FIG.7,

[0042]FIG. 10 is a view of the configuration of a principal part of athird concrete example of the content distribution system shown in FIG.7,

[0043]FIG. 11 is a flowchart for explaining decision processing in adecision controller of a set top box shown in FIG. 10,

[0044]FIG. 12 is a view of the configuration of a principal part of afourth concrete example of the content distribution system shown in FIG.7,

[0045]FIG. 13 is a flowchart for explaining the decision processing inthe decision controller of the set top box shown in FIG. 12,

[0046]FIG. 14 is a view of the configuration of a principal part of afifth concrete example of the content distribution system shown in FIG.7, and

[0047]FIG. 15 is a view of the configuration of a principal part of asixth concrete example of the content distribution system shown in FIG.7.

BEST MODE FOR CARRYING OUT THE INVENTION

[0048] Preferred embodiments of the present invention will be explainednext referring to the attached drawings.

[0049] First Embodiment

[0050] Below, an explanation will be made of a first embodiment of thepresent invention by referring to the drawings.

[0051]FIG. 1 is a conceptual view of a signal transfer system fortransferring a digital image signal of content. A transmitter (forexample a computer system or set top box) 10 for transmitting the imagesignal and a receiver (display device, television set, etc.) 40 forreceiving the image signal and displaying the image are connected viaDVI specification channels 30. The DVI specification channels 30 areprovided with a TMDS channel for transferring the digital image signal,a bi-directional channel used for DDC (display data channel)specification information transfer relating to plug and play establishedby the VESA (Video Electronics Standard Association), a power supplyline, and a hot plug detection use signal line.

[0052]FIG. 2 is a view of a pin arrangement of a DVI specificationconnector. Note that the figure shows the case where a channel fortransferring an analog image signal is provided. Pins “1” to “5”, “9” to“13”, and “17” to “24” are for TMDS channels, pins “6” and “7” are forDDC use bi-directional channels (I²C bus), and pins “C1” to “C5” are forchannels for analog image signals. Further, pins “14” and “15” are for a5V power supply line and a ground line, and a pin “16” is defined as fora hot plug detection use signal line.

[0053] An image signal generator 11 of the transmitter 10 shown in FIG.1 generates a three-primary color image signal DG of the content by aresolution and number of colors optimum with respect to the receiver 40based on a signal generation control signal GC supplied from a DDCprotocol processing circuit 152 mentioned later and supplies the same toan encryption circuit 121 of a transmission processor 12, a terminal aof a signal selection circuit 122, and a protection information detector13.

[0054] The encryption circuit 121 of the transmission processor 12encrypts the three-primary color image signal DG by for example anencryption key KC and supplies it as the three-primary color imagesignal DGE to a terminal b of the signal selection circuit 122. Amoveable terminal c of the signal selection circuit 122 is connected toone terminal of the output control switch 123, is controlled by aprotection operation control signal PT supplied from a authenticationprocessing circuit 151 of a transmission controller 15 mentioned later,and selects either of the non-encrypted three-primary color image signalDG supplied to the terminal a or the encrypted three-primary color imagesignal DGE supplied to the terminal b.

[0055] The other terminal of the output control switch 123 is connectedto a TMDS transmission circuit 124. The on/off operation of this outputcontrol switch 123 is also controlled by a protection operation controlsignal PU from the authentication processing circuit 151.

[0056] The TMDS transmission circuit 124 encodes the three-primary colorimage signal selected at the signal selection circuit 122 and suppliedvia the output control switch 123, tries to balance a DC level andminimize the number of times of inversion of the logic level, andconverts the signal to a baseband serial transfer signal SD suitable fortransfer. The serial transfer signal SD for each color is output from aconnector 17 to a channel 30. Note that a horizontal synchronizationsignal and a vertical synchronization signal of the three-primary colorimage signal DG are inserted in a blanking period of for example a blueimage signal and transmitted.

[0057] The protection information detector 13 detects whether to providecopyright protection according to the copyright protection informationof the three-primary color image signal DG and supplies a decisionsignal PD to the authentication processing circuit 151. As thiscopyright protection information, use is made of CGMS (copy generationmanagement system) information indicating if the content can be freelycopied or copying is prohibited or whether to recognize only one copy orCCI (copy control information) etc. Also, when an analog image signal issupplied to the image signal generator 11 and this analog image signalis transferred converted to a digital signal, it is also possible todecide whether or not to provide copy protection based on an APS (analogprotection system) signal for copyright protection used in the analogimage signal.

[0058] The authentication processing circuit 151 of the transmissioncontroller 15 is comprised using an electrically programmablenonvolatile memory. This authentication processing circuit 151 registersin it classification information of receivers to be connected to thetransmitter 10, for example, the model names of the receivers. As theclassification information registered in this authentication processingcircuit 151, classification information indicating the receivers nothaving a function for copying the content without inviting degradationof the quality of image etc., for example, classification informationindicating the receivers not having a function for outputting thesupplied digital image signal or converting the digital image signal tofor example an NTSC system video signal and outputting the same isregistered. Also, the authentication processing circuit 151 decideswhether or not the model name of the receiver indicated by hardwareinformation RR supplied from the DDC protocol processing circuit 152mentioned later is registered and generates the protection operationcontrol signals PT and PU and supplies them to the transmissionprocessor 12 based on this decision result and the decision signal PDsupplied from the protection information detector 13.

[0059] The DDC protocol processing circuit 152 communicates with thereceiver 40 via the connector 17 and the channels 30 in accordance withthe DDC protocol and supplies the hardware information RR supplied fromthe receiver 40 to the authentication processing circuit 151. Also, theDDC protocol processing circuit 152 performs the authenticationprocessing with the connected receiver 40 based on the decision resultat the protection information detector 13 so as to decide whether or notthe connected receiver 40 is based on the new specification includingthe encryption technology for copyright protection. Here, when it isconfirmed that the receiver 40 is based on the new specification, thecircuit performs processing for supplying the encryption key KC usedwhen encrypting the three-primary color image signal DG to the receiver40. Note that the encryption key KC may be held in the DDC protocolprocessing circuit 152, may be supplied from the DDC protocol processingcircuit 152 to the encryption circuit 121, or may be read out by the DDCprotocol processing circuit 152 from the encryption circuit 121 whensupplying the encryption key KC to the receiver 40.

[0060] Further, the DDC protocol processing circuit 152 generates thetransfer control signal TC and supplies the same to the TMDStransmission circuit 124 so as to control the generation and transferprocessing of the baseband serial transfer signals SD performed at theTMDS transmission circuit 124.

[0061] A connector 41 of the receiver 40 has a reception processor 42and a reception controller 43 connected to it. The reception processor42 generates the three-primary color image signal DS based on receivedserial transfer signal SD and supplies it to a display 44. When adecryption circuit for decrypting the encrypted three-primary colorimage signal is provided in the reception processor 42 and theencryption key KC transferred from the transmitter 10 is supplied fromthe reception controller 43, the circuit performs the decryptionprocessing of the encrypted three-primary color image signal using thisencryption key KC.

[0062] Next, an explanation will be made of the operation of thetransmitter 10 by using the flowchart of FIG. 3. At step ST1, thetransmitter communicates with the connected receiver 40 to obtain themodel name, resolution, or other hardware information relating to thereceiver 40 and generates a signal generation control signal GC based onthis hardware information for supply to the image signal generator 11.

[0063] At step ST2, it is decided based on the decision signal PDwhether or not the content supplied from the transmitter 10 to thereceiver 40 is copyright protected. Here, when it is decided based onthe decision signal PD from the protection information detector 13 thatthe content is not copyright protected, the routine proceeds to stepST3, where the moveable terminal c of the signal selection circuit 122is set to the terminal a side by the protection operation control signalPT and the unencrypted three-primary color signal DG is selected, thenthe routine proceeds to step ST9.

[0064] Also, when it is decided at step ST2 that the content iscopyright protected, the routine proceeds to step ST4, where theauthentication processing with the receiver 40 is carried out, and it isdecided whether or not the connected receiver 40 is based the newspecification including the encryption technology for copyrightprotection. This authentication processing assumes that for example acommon key method is utilized, sends the data from the transmitter 10 tothe receiver 40, and encrypts and returns the data by the common keyheld at the receiver 40. If this returned encrypted data is inverselyconverted by the common key and it can be confirmed that the transmitteddata appears, it can be correctly decided that the receiver is based onthe new specification. Also, if a public key system is utilized, thedata is encrypted by the public key of the receiver 40 and sent from thetransmitter 10, the data decrypted by a secret key is returned from thereceiver 40, and it can be confirmed that this returned data is equal tothe data which was encrypted and transmitted, it can be correctlydecided that the receiver is based on the new specification.

[0065] When it is decided at step ST4 that the receiver 40 is based onthe new specification, the routine proceeds to step ST5, where theencryption key KC used at the encryption circuit 121 is supplied fromthe DDC protocol processing circuit 152 to the reception controller 43,then the routine proceeds to step ST6.

[0066] At step ST6, the moveable terminal c of the signal selectioncircuit 122 is set to the terminal b side by the protection operationcontrol signal PT so as to select the encrypted three-primary colorimage signal DGE, then the routine proceeds to step ST9.

[0067] When it is not decided at step ST4 that the receiver 40 is basedon the new specification, the routine proceeds to step ST7, where it isdecided whether or not the model name of the receiver 40 indicated bythe hardware information RR supplied from the DDC protocol processingcircuit 152 is registered in the authentication processing circuit 151.Here, when it is decided that the model name of the receiver isregistered and the receiver does not have a function enabling it to copycontent without inviting degradation of the quality of image etc., theroutine proceeds to step ST8. Also, when it is not registered, theroutine proceeds to step ST10.

[0068] At step ST8, the moveable terminal c of the signal selectioncircuit 122 is set to the terminal a side by the protection operationcontrol signal PT so as to select the unencrypted three-primary colorimage signal DG, then the routine proceeds to step ST9.

[0069] When the routine proceeds from step ST3 or step ST6 or step ST8to step ST9, the output control switch 123 is turned on by theprotection operation control signal PU to generate the serial transfersignal SD based on the unencrypted three-primary color image signal DGor the encrypted three-primary color image signal DGE selected at thesignal selection circuit 122 and transmit it to the receiver 40. Also,when the routine proceeds from step ST7 to step ST10, at step ST10, theoutput control switch 123 is turned off by the protection operationcontrol signal PU and the transfer of the serial transfer signal SDbased on the three-primary color image signal DG or DGE is prohibited.

[0070] When copyright protection of the content to be transferred isnecessary in this way, when a receiver based on the new specificationincluding encryption technology for copyright protection is connected,the content is transmitted encrypted, so illicit copying of the contentcan be prevented. Also, even if a receiver 40 not based on the newspecification is connected, when it is confirmed that this connectedreceiver is hardware not having a function of copying the content, thecontent is transmitted without being encrypted, therefore not only canillicit copying of the content be prevented, but also even a receivernot based on the new specification can be made to correctly display theimage of the content.

[0071] Further, while a digital image signal of content requiringencryption is being transmitted without encryption, it is monitoredwhether or not there has been a change of connection of the receiver,that is, if the receiver 40 connected to the transmitter 10 has beendisconnected or the receiver 40 has been changed. A change of connectionof the receiver is monitored by utilizing for example the hot plugdetection function or plug and play function. Here, if the hot plugdetection function is utilized, it can be decided whether or not theconnection of the receiver was changed according to whether or not thereceiver was disconnected by the hot plug detection use signal line.Also, if the plug and play function is utilized, it is possible toperform the processing for confirmation of the receiver by the plug andplay function even during the transfer of the image signal and thereforedecide whether or not there has been a change in connection of thereceiver during the transfer of the image signal.

[0072] When it is decided that there has not been a change in connectionduring this monitoring of a change of connection of the receiver, theoutput control switch 123 is held in the on state by the protectionoperation control signal PU, while when it is decided that there hasbeen a change in connection, the signal selection circuit 122 and theoutput control switch 123 are controlled by the protection operationcontrol signals PT and PU so that the unencrypted three-primary colorimage signal DG is not transmitted. For example, by turning the outputcontrol switch 123 off by the protection operation control signal PU,the transfer of the unencrypted three-primary color image signal DG canbe stopped. Also, by switching the moveable terminal c of the signalselection circuit 122 to the terminal b side by the protection operationcontrol signal PT and selecting the encrypted three-primary color imagesignal DGE, the unencrypted three-primary color image signal DG can beprevented from being transferred.

[0073] In this way, even when there is a change in the connection of thereceiver while the image signal of the content is being transferredwithout encryption and, for example, a receiver having a function forcopying content without inviting degradation of the quality of imageetc. is connected, the unencrypted three-primary color image signal DGis no longer automatically transferred, so the illicit copying of thecontent can be prevented.

[0074] The authentication processing circuit 151 is configured using aprogrammable nonvolatile memory, so new model names can be added to theauthentication processing circuit 151. Here, if the informationregistered in the authentication processing circuit 151 were tamperedwith and the model name of a receiver having a function for copying thecontent without inviting degradation of the quality of image etc. wereregistered, the content could be illicitly copied.

[0075] For this reason, the authentication processing circuit 151 uses ameans having a high safety so as to prevent the stored information frombeing tampered with. For example, the hardware is configured so that theinformation is lost at the time of reverse engineering of theauthentication processing circuit 151 or the circuit is configured tomake analysis of the information difficult. Also, when updating thestored information, in the same way as the above authenticationprocessing, it is decided whether or not the hardware connected to thetransmitter for updating the stored information is correct by utilizingthe common key system or the public key system and the update of thestored information is permitted only when it is decided that theapparatus is correct. Further, when the transmitter is hardware such asa set top box, it is also possible to encrypt the information to beupdated and supply it to the set top box from the broadcast station sideby using the information transmission use channel and have the set topbox decrypt the encrypted information by using he secret key stored inan IC card or the like unique to the viewer and update the storedinformation by using the decrypted information. Also, the transmitter isa computer system.

[0076] Note that, in the first embodiment, whether or not the content iscopyright protected is determined by using a three-primary color imagesignal DG, but even if information on whether or not the three-primarycolor image signal DG must be processed for copyright protection issupplied by the image signal generator 11 to the transmission controller15, it is possible to similarly operate the transmitter 10. Further, thesignal of the content to be transferred is not limited to an imagesignal and of course may also be a voice signal.

[0077] In this way, according to the first embodiment, even if areceiver not based on this new specification is connected to atransmitter based on the new specification including the encryptiontechnology for copyright protection, it is possible to register thisreceiver not based on the new specification in the transmitter so as toenable a signal output from a transmitter based on the new specificationto be received at the receiver not based on the new specification andthe content to be used.

[0078] Second Embodiment

[0079] Next, the content distribution system and content distributionmethod enabling a content owner to directly control copying as desiredwhile using a standard apparatus as the processing apparatus after thereceiver will be explained as a second embodiment of the presentinvention by referring to FIG. 13 to FIG. 15.

[0080] Overall Configuration

[0081] First, an overall configuration of the content distributionsystem of the second embodiment will be explained by referring to FIG.7.

[0082]FIG. 7 is a view of the overall schematic configuration of acontent distribution system 1100 of the second embodiment.

[0083] The content distribution system 1100 has a content owner 1200,broadcaster 1300, broadcast network 1400, set top box 1500, displaydevice I/F 1600, and display device 1700.

[0084] First, the configuration of each part will be explained.

[0085] The content owner 1200 is the owner of the content to bedistributed, encrypts the content to be distributed by using a desiredencryption key Ka, and provides the content in the encrypted state tothe broadcaster 1300. In the present embodiment, the “content” meanscontent including images and sound, for example, TV programs or movies.

[0086] Note that the “encryption” referred to here broadly meansprocessing the content data itself or any additional data or the likedesired by the content owner 1200 to a state preventing it from beingchanged in any way, read, or used. Accordingly, it specifically includessuperimposing additional data in the form of an electronic watermarketc. when actually encrypting content data. Note that, the actualconcrete processing content will be explained at the later more concreteexplanation of the configuration.

[0087] The broadcaster 1300 further performs encryption for conditionalaccess by using an encryption key Kb on the content in the encryptedstate provided by the content owner 1200 and distributes the same viathe broadcast network 1400.

[0088] The broadcast network 1400 is any data distributing meansincluding any data distribution system via the communication networkgoing through a communication network such as a digital ground wavebroadcast, digital satellite broadcast, CATV, or the Internet anddistributes the content data transferred by the broadcaster 1300 to anyuser.

[0089] The set top box 1500 is a receiver provided in for example thehome of each user and receiving the data transferred by the broadcaster1300 via the broadcast network 1400 based on an operation of the user.

[0090] The set top box 1500 decrypts the content data by using theencryption key Ka delivered based on for example a contract in advancewhen receiving the content data selected by the user. Then, it encryptsthe decrypted content data again by using the encryption key Kc set inadvance and transfers it to the display device I/F 1600. In the presentembodiment, the set top box 1500 and the display device 1700 areconnected using IEEE1394 as the interface, then the set top box 1500encrypts the content data again by the 5C encryption scheme defined inthe IEEE1394.

[0091] The display device I/F 1600 is a connecting means between the settop box 1500 and the display device 1700 and is the IEEE1394 in thepresent embodiment as mentioned before.

[0092] The display device 1700 decrypts the encrypted content data inputfrom the set top box 1500 via the display device I/F 1600 by using theencryption key Kc set in advance and displays the same in auser-viewable manner.

[0093] Next, the basic overall operation of the content distributionsystem 1100 having such a configuration will be explained.

[0094] First, the content to be distributed is encrypted by the owner,that is, the content owner 1200, by using the encryption key Ka, thentransferred to the broadcaster 1300, then is further encrypted forconditional access by the broadcaster 1300 by using the encryption keyKb and transferred to the broadcast network 1400.

[0095] The data transferred to the broadcast network 1400 isspecifically substantially received by the viewer (user of the content)selected to be viewed from the set top box 1500 operated by the user andthe encryption for the conditional access is first decrypted by aninternal decryptor. The encryption key Ka at this time is provided inthe form of a secure storage medium such as an IC card when the userconcludes a reception contract with the broadcaster 1300 in advance.

[0096] The decrypted content data is encrypted again by the 5C scheme ofthe IEEE1394 by using the encryption key Kc set in advance and istransferred to the display device 1700.

[0097] Then, it is decrypted at the display device 1700 and displayed ina user viewable manner.

[0098] Note that the operation performed by the viewer on the set topbox 1500 such as the selection of the content data to be received andthe transfer of the content data from the set top box 1500 to thedisplay device 1700 is successively stored in the charge informationmemory in the set top box 1500 and used for the charging accompanyingthe reception of content.

[0099] In this way, in the content distribution system 1100, the contentowner 1200 itself substantially encrypts the content to be distributed.The encryption is not decrypted until the set top box 1500 of the user.Accordingly, if the control information for controlling for example thereproduction or copying of the content data on the user side isencrypted and superimposed on the content data, the content owner 1200itself can control the usage of the content data on the user side.Namely, a change of the usage state, usage conditions, etc. of thecontent set by the broadcaster 1300 can be prevented regardless of thereason.

[0100] Also, in the content distribution system 1100, a standardinterface can be used between the set top box 1500 and the displaydevice 1700 while placing the usage of the content within a range ofsuch control of the content owner 1200. Also, the standard hardwarecompatible with that interface can be used as the display device 1700.

[0101] Example of Concrete Application

[0102] The basic overall configuration of the content distributionsystem 1100 according to the present invention was explained above, butan example of a more concrete configuration and concrete form ofapplication will be explained as a first concrete example to fifthconcrete example.

[0103] Note that all of the broadcast network 1400, display device I/F1600, and display device 1700 are standard, therefore, in the followingexplanation, the illustration of these in the drawings and explanationsthereof will be omitted.

[0104] First Concrete Example

[0105] A first example of concrete application of the contentdistribution system 1100 will be explained by referring to FIG. 8.

[0106] As the first concrete example, a system wherein the content owner1200 superimposes the control information for controlling the usage ofthe content on the content data in the form of an electronic watermarkand distributes the same and wherein the usage of the content datareceived by the user is controlled by this will be illustrated.

[0107]FIG. 8 is a view of the configuration of the content owner 1200 tothe set top box 1500 of the first concrete configuration of the contentdistribution system 1100.

[0108] In the first concrete configuration shown in FIG. 8, the contentowner 1200 has an electronic watermark superimposer 1208 whichsuperimposes the copy control information for controlling the usage ofthe content which becomes valid in the set top box 1500 on the contentdata in the form of an electronic watermark.

[0109] Further, the content owner 1200 has an encryptor 1210 whichencrypts the content data with the electronic watermark superimposedthereon by using the encryption key Ka.

[0110] Then, it transfers this encrypted content data to the broadcaster1300.

[0111] The broadcaster 1300 has the encryptor 1302 which furtherperforms encryption for conditional access by using the encryption keyKb on the content data input from the content owner 1200 and transmitsthe same.

[0112] The set top box 1500 has a decryptor 1502, decryptor 1504,electronic watermark detector 1506, 5C encryptor 1508, output switch1510, and charge information memory 1524.

[0113] The decryptor 1502 decrypts the encrypted signal received fromthe broadcaster 1300 by using the encryption key Kb. Namely, it decryptsthe encryption for the conditional access. The decrypted signal is thesignal encrypted by the content owner 1200 and can not yet used.

[0114] The decryptor 1504 further decrypts the signal decrypted at thedecryptor 1502 by using the encryption key Ka and outputs the decryptedsignal to the electronic watermark detector 1506, 5C encryptor 1508, andthe output switch 1510. The signal decrypted at the decryptor 1504 isthe signal obtained by the superimposition of the copy controlinformation on the baseband content data as the electronic watermark.

[0115] The electronic watermark detector 1506 detects the copy controlinformation superimposed as the electronic watermark from the signaldecrypted at the decryptor 1504, generates the signal for controllingthe signal to be output from the set top box 1500, concretely the signalfor controlling the output switch 1510 based on this, and applies thesame to the output switch 1510.

[0116] The 5C encryptor 1508 encrypts the signal decrypted at thedecryptor 1504 by the 5C scheme by using the encryption key Kc andapplies the same to the output switch 1510.

[0117] The output switch 1510 selects either of the unencrypted contentdata output from the decryptor 1504 or the content data encrypted at the5C encryptor 1508 as the output signal from the set top box 1500 basedon the control signal applied from the electronic watermark detector1506 and outputs the same from the set top box 1500.

[0118] The charge information memory 1524 detects and stores theinformation relating to the charge accompanying the usage of the contentdata by detecting the signal substantially output from the set top box1500 or monitoring the information input from the display device 1700via the IEEE1394. The information stored in the charge informationmemory 1524 is suitably transmitted to a predetermined settlementmanager where the charge processing is performed.

[0119] In such a set top box 1500, the encryption for the conditionalaccess applied at the decryptor 1502 by the broadcaster 1300 isdecrypted, the encryption applied by the content owner 1200 itself isdecrypted at the decryptor 1504, and the copy control information addedby the content owner 1200 superimposed as the electronic watermark isdetected at the electronic watermark detector 1506 from that decryptedcontent data.

[0120] Then, when for example this copy control information describes tooutput the encrypted content data from the set top box 1500, the dataobtained by encrypting the output from the decryptor 1504 at the 5Cencryptor 1508 using the encryption key Kc is selected by the outputswitch 1510 based on the control signal from the electronic watermarkdetector 1506 and output from the set top box 1500 to a not illustrateddisplay device.

[0121] Also, when the copy control information describes thatunencrypted content data can be output from the set top box 1500, theoutput from the decryptor 1504 is selected by the output switch 1510based on the control signal from the electronic watermark detector 1506and output from the set top box 1500.

[0122] In this way, in the first concrete example, the content owner1200 superimposes the copy control information on the content data inthe form of the electronic watermark and further performs encryption.The content owner 1200 itself can directly control the output of thereception side without intervention by the broadcaster 1300.

[0123] Second Concrete Example

[0124] A second example of concrete application of the contentdistribution system 1100 will be explained next by referring to FIG. 9.

[0125] The second concrete example is configured as the first concreteexample without the encryptor 1210 of the content owner 1200 andomitting the encryption processing. Also, along with this, the set topbox 1500 is also configured omitting the decryptor 1504.

[0126] In such a configuration, the content owner 1200 superimposes thecopy control information in the form of an electronic watermark at theelectronic watermark superimposing unit 1208 and provides the contentdata in that state to the broadcaster 1300 as it is, that is, withoutencryption.

[0127] Then, the broadcaster 1300 performs the encryption for theconditional access on this at the encryptor 1302 and transfers theresult.

[0128] The set top box 1500 receiving the transferred signal decryptsthe encryption for conditional access at the decryptor 1502 to directlyobtain content data not encrypted in any way, detects the copy controlinformation superimposed as the electronic watermark at the electronicwatermark detector 1506, and controls the output switch 1510 by this.

[0129] The operations of the 5C encryptor 1508, output switch 1510, notillustrated charge information memory, etc. are the same as those of thefirst concrete example.

[0130] In this way, the second concrete example omits the encryptor 1210in the content owner 1200 and the decryptor 1504 of the set top box1500, so can simplify the configurations of the devices.

[0131] In such a configuration, the encryption processing by theencryptor 1210 of the content owner 1200 is eliminated, therefore thecontent data in the unencrypted state is transferred to the broadcaster1300. The output of the set top box 1500, however, is controlled by theelectronic watermark information. Further, the electronic watermark datais superimposed. Therefore, illicit usage can be traced, so thepossibility of illicit usage can be said to be low.

[0132] If such a condition is acceptable, this simple configurationsecond concrete example is effective.

[0133] Third Concrete Example

[0134] An explanation will be made of a third concrete applicationexample of the content distribution system 1100 by referring to FIG. 10and FIG. 11.

[0135] The third concrete example is configured by the broadcaster 1300adding a unique control descriptor separate from that added by thecontent owner 1200.

[0136] Specifically, the processing in the content owner 1200 is thesame as the processing of the first concrete example. First the copycontrol information for controlling the usage of the content whichbecomes valid in the set top box 1500 is superimposed on the contentdata in the form of an electronic watermark. Next, the encryptor 1210encrypts the content data with the electronic watermark superimposedthereon by using the encryption key Ka and transfers this encryptedcontent data to the broadcaster 1300.

[0137] The broadcaster 1300 adds the unique control descriptor to theencrypted content data transferred from the content owner 1200 in acontrol descriptor adder 1306, encrypts this in the encryptor 1302 byusing the encryption key Kb, and transmits the same.

[0138] The set top box 1500 receiving this decrypts the encryption forthe conditional access performed by the broadcaster 1300 in thedecryptor 1502 by using the encryption key Kb.

[0139] From this decrypted signal, the control descriptor added by thebroadcaster 1300 is detected at the control descriptor detector 1512 andoutput to a decision controller 1514.

[0140] Also, the signal decrypted at the decryptor 1502 is furtherdecrypted at the decryptor 1504 by using the encryption key Ka.

[0141] The electronic watermark detector 1506 detects the copy controlinformation superimposed in the form of an electronic watermark by thecontent owner 1200 from this decrypted signal and outputs it to thedecision controller 1514.

[0142] The decision controller 1514 performs the decision forcontrolling the usage of the received content data based on the copycontrol information set by the content owner 1200 and input from theelectronic watermark detector 1506 and the control descriptor set by thebroadcaster 1300 and input from the control descriptor detector 1512 andcontrols the output data based on that decision.

[0143] Here, it is assumed that the copy control information and thecontrol descriptor set to output the content data from each set top box1500 by either transfer by 5C encryption or by transfer withoutencryption. In that case, the decision controller 1514 performs adecision according to the flowchart as shown in for example FIG. 11.

[0144] Namely, when the decision is started (step S10), first, the copycontrol information input from the electronic watermark detector 1506 isreferred to so as to judge whether it sets 5C encryption (step Sll).When it sets 5C encryption, a control signal for selecting the output ofthe 5C encryptor 1508 is output to the output switch 1510, whereby 5Cencrypted content data is output from the set top box 1500 (step S12).

[0145] When the copy control information input from the electronicwatermark detector 1506 does not set 5C encryption (step Sll), thecontrol descriptor input from the control descriptor detector 1512 isreferred to so as to judge whether or not it sets 5C encryption (stepS13). Then, when it sets 5C encryption, in the same way as the casewhere the copy control information sets it, a control signal forselecting the output of the 5C encryptor 1508 is output to the outputswitch 1510, whereby 5C encrypted content data is output from the settop box 1500 (step S12).

[0146] Even when the control descriptor input from the controldescriptor detector 1512 does not set 5C encryption (step S13), thedecision controller 1514 outputs a control signal for selecting theoutput from the decryptor 1504 to the output switch 1510 to make the settop box 1500 output the unencrypted content data (step S14).

[0147] In this way, the third concrete example enables the content owner1200 and the broadcaster 1300 to independently set control of the usageof the content data. Then, it is possible to freely set which settingshould be given priority and what kind of control is to be carried outby changing an algorithm set in the decision controller 1514.

[0148] BAy employing the algorithm as shown in for example FIG. 11, itis possible to execute the setting of the content owner 1200 withpriority over the setting of the broadcaster 1300.

[0149] Fourth Concrete Example

[0150] Next, a fourth example of concrete application of the contentdistribution system 1100 will be explained by referring to FIG. 12 andFIG. 13.

[0151] The fourth concrete example is configured similar to the thirdconcrete example, but the copying is controlled by the content owner1200 not by superimposing an electronic watermark on the content data,but by adding a control descriptor to the content data in the same wayas the broadcaster 1300.

[0152] Namely, the content owner 1200 adds copy control information forcontrolling the usage of the content which becomes valid in the set topbox 1500 to the content data in the form of a control descriptor(control descriptor 1) by a control descriptor adder 1212. Then, thecontent data with the control descriptor added thereto is encrypted atthe encryptor 1210 by using the encryption key Ka and the encryptedcontent data is transferred to the broadcaster 1300.

[0153] The broadcaster 1300 adds a unique control descriptor (controldescriptor 2) to the encrypted content data transferred from the contentowner 1200 at the control descriptor adder 1306, encrypts this at theencryptor 1302 by using the encryption key Kb, and transfers the same.

[0154] The set top box 1500 receiving this decrypts the encryption forthe conditional access performed by the broadcaster 1300 at thedecryptor 1502 by using the encryption key Kb. A control descriptor 2detector 1512 detects the control descriptor 2 added by the broadcaster1300 from this decrypted signal and outputs the result to the decisioncontroller 1514.

[0155] The signal decrypted at the decryptor 1502 is further decryptedat the decryptor 1504 by using the encryption key Ka. Then, a controldescriptor 1 detector 1516 detects the control descriptor 1 added by thecontent owner 1200 from this decrypted signal and outputs it to thedecision controller 1514.

[0156] The decision controller 1514 performs the decision forcontrolling the usage of the received content data based on the controldescriptor 1 set by the content owner 1200 input from the controldescriptor 1 detector 1516 and the control descriptor 2 set by thebroadcaster 1300 input from the control descriptor 2 detector 1512 andcontrols the output data based on that decision.

[0157] Here, it is assumed that the control descriptor 1 and the controldescriptor 2 set to output the content data from each set top box 1500by either transfer by 5C encryption or by transfer without encryption.In that case, the decision controller 1514 performs a decision accordingto the flowchart as shown in for example FIG. 13.

[0158] Namely, when the decision is started (step S20), first, thecontrol descriptor 1 input from the control descriptor 1 detector 1516is referred to so as to judge whether it sets 5C encryption (step S21).When it sets 5C encryption, a control signal for selecting the output ofthe 5C encryptor 1508 is output to the output switch 1510, whereby 5Cencrypted content data is output from the set top box 1500 (step S22).

[0159] When the control descriptor 1 input from the control descriptor 1detector 1516 does not set 5C encryption (step S21), the controldescriptor 2 input from the control descriptor 2 detector 1512 isreferred to so as to judge whether or not it sets 5C encryption (stepS23). Then, when it sets 5C encryption, in the same way as the casewhere the control descriptor 1 sets this, a control signal for selectingthe output of the 5C encryptor 1508 is output to the output switch 1510,whereby 5C encrypted content data is output from the set top box 1500(step S22).

[0160] When the control descriptor 2 input from the control descriptor 2detector 1512 also does not set 5C encryption (step S23), the decisioncontroller 1514 outputs a control signal for selecting the output fromthe decryptor 1504 to the output switch 1510, whereby unencryptedcontent data is output from the set top box 1500 (step S24).

[0161] In this way, in the fourth concrete example, the content owner1200 and the broadcaster 1300 can independently set control of the usageof the content data in the form of adding a control descriptor. Further,they can freely set how to give priority to what setting and how tocontrol the same by changing an algorithm set in the decision controller1514.

[0162] Further, by employing the algorithm as shown in for example FIG.13, it is possible to execute the setting of the content owner 1200 withpriority over the setting of the broadcaster 1300.

[0163] Fifth Concrete Example

[0164] A fifth example of concrete application of the contentdistribution system 1100 will be explained next by referring to FIG. 14.

[0165] The fifth concrete example enables suitable control of copyingeven with respect to analog output from the set top box 1500.

[0166] In this case, first, the content owner 1200 superimposes the copycontrol information desired to be set on the content data in the form ofan electronic watermark by the electronic watermark superimposer 1208.This electronic watermark information is used for the copy protection ofthe analog output from the set top box 1500.

[0167] Further, the content owner 1200 encrypts the content data withthe electronic watermark information superimposed thereon at theencryptor 1210 by using the encryption key Ka. The content owner 1200transfers both this encrypted content data and the previous copy controlinformation to the broadcaster 1300.

[0168] The broadcaster 1300 converts the copy control informationtransferred from the content owner 1200 to the control descriptor, thenadds this to the encrypted content data transferred from the contentowner 1200 at the control descriptor adder 1306, encrypts the same atthe encryptor 1302 by using the encryption key Kb, and transfers thesame.

[0169] The set top box 1500 receiving this decrypts the encryption forthe conditional access performed by the broadcaster 1300 at thedecryptor 1502 by using the encryption key Kb. The control descriptordetector 1512 detects the control descriptor added by the broadcaster1300 from this decrypted signal upon instruction from the content owner1200 and generates a control signal for controlling the output switch1510 and applies it to the output switch 1510.

[0170] Further, the signal decrypted at the decryptor 1502 is furtherdecrypted at the decryptor 1504 by using the encryption key Ka. Thisdecrypted signal is 5C encrypted at the 5C encryptor 1508 or directlyapplied to the output switch 1510. Either is selected at the outputswitch 1510 and output as the digital output.

[0171] On the other hand, the signal decrypted at the decryptor 1502 isinput to an analog signal encoder 1518, converted to an analog signalhere, and output from the set top box 1500.

[0172] In this way, in the fifth concrete example, particularly, it ispossible to output from the set top box 1500 an adequately rightprocessed analog signal with the copyright protection informationsuperimposed thereon by the electronic watermark. Accordingly, this ispreferred where an analog signal output is required.

[0173] Note that, in the configuration shown in FIG. 14, the copycontrol information requested by the content owner 1200 is converted toa control descriptor by the broadcaster 1300 and added to the contentdata. If the broadcaster 1300 is a sufficiently reliable institution,there is no problem in employing such a configuration. However, when thecontent owner 1200 sets control itself for a certain reason, in the sameway as the case of the third concrete example, the control descriptormay also be set by the content owner 1200.

[0174] Sixth Concrete Example

[0175] An explanation will be made of a sixth example of concreteapplication of the content distribution system 1100 by referring to FIG.15.

[0176] In the sixth concrete example, the digital output from the settop box 1500 is made either of monitor connection use DVI (digitalvisual interface) and copyright protected output (DVI-CP) and enable theanalog output to be turned ON/OFF.

[0177] In this case, the content owner 1200 superimposes the copycontrol information desired to be set on the content data in the form ofan electronic watermark at the electronic watermark superimposing unit1208, encrypts the content data with that electronic watermarkinformation superimposed thereon at the encryptor 1210 by using theencryption key Ka, and transfers the encrypted content data to thebroadcaster 1300.

[0178] The broadcaster 1300 adds the unique control descriptor to theencrypted content data transferred from the content owner 1200 at thecontrol descriptor adder 1306, then performs the encryption for theconditional access at the encryptor 1302 by using the encryption key Kband transfers the same.

[0179] The set top box 1500 receiving this decrypts the encryption forthe conditional access performed by the broadcaster 1300 at thedecryptor 1502 by using the encryption key Kb, detects the controldescriptor added by the broadcaster 1300 from this decrypted signal atthe control descriptor detector 1512, and outputs the same to thedecision controller 1514.

[0180] Also, the signal decrypted at the decryptor 1502 is furtherdecrypted at the decryptor 1504 by using the encryption key Ka, and thecopy control information superimposed in the form of the electronicwatermark by the content owner 1200 is detected from this decryptedsignal at the electronic watermark detector 1506 and output to thedecision controller 1514.

[0181] The decision controller 1514 performs the decision forcontrolling the usage of the received content data based on the copycontrol information set by the content owner 1200 input from theelectronic watermark detector 1506 and the control descriptor set by thebroadcaster 1300 input from the control descriptor detector 1512 andcontrols the output data based on the decision.

[0182] Concretely, the decision controller 1514 performs a decision asto whether to output the baseband data or output data encrypted by theDVI-CP as the digital output from the set top box 1500, makes a decisionas to whether or not to output an analog signal, and outputs controlsignals based on the results of the decision to the output switch 1510and an analog output switch 1522.

[0183] Further, the signal decrypted at the decryptor 1504 is encryptedto DVI-CP at an encryptor 1520 or directly applied to the output switch1510. Either is selected at the output switch 1510 and output as thedigital output.

[0184] On the other hand, the signal decrypted at the decryptor 1504 isinput to the analog signal encoder 1518, converted to an analog signalhere, applied to the analog output switch 1522, selected at the analogoutput switch 1522 under the control of the decision controller 1514,and output as the analog output.

[0185] In this way, in the sixth concrete example, a digital videosignal can be output from the set top box 1500 by DVI as the RGBbaseband signal or an encoded signal. Also, a suitably right processedanalog signal with the copyright protection information superimposedthereon by the electronic watermark can be selectively output.

[0186] Modification

[0187] Note that the present invention is not limited to the aboveembodiments. Various preferred modifications are possible.

[0188] For example, the apparatus connected to the set top box 1500 andused in the content distribution system 1100 was a display device fordisplaying a video signal, but the invention is not limited to this. Anyimage processing device can be connected too. For example, it is alsopossible to connect a recording device for recording the output data orconnect a transfer device for transferring the output data.

[0189] Further, the output I/F of the set top box 1500 is not limited tothe IEEE1394 and DVI shown in the above embodiments. Any I/F can beused.

[0190] Further, the means for transmitting the data between thebroadcaster 1300 and the set top box 1500 is not limited to abroadcasting means. Any information transmitting means can be applied.

[0191] Further, not limited to a so-called broadcast, a transferringmeans for transmitting the desired content data to a requesting set topbox 1500 in response to a request from the set top box 1500 can be usedtoo.

[0192] Further, in the present embodiment, the content to be distributedwas a video signal and a video signal containing an audio signal, but itis not limited to this. It can be applied to the distribution of anycontent data. For example, it can be used as a distribution system ofaudio data, still image data, game software programs, any programsoftware, etc.

[0193] As explained above, in the present invention illustrated in thefirst and second embodiments, information indicating a receiver nothaving a function enabling copying of content indicated by the contentsignal is held by utilizing the transferred content signal. Wheninformation indicating the connected receiver is included in this heldinformation, the non-copyright protected content signal is transmitted.For this reason, a signal compatible with the receiver can betransmitted in accordance with whether or not the receiver has afunction enabling copying of the content.

[0194] Further, when it is decided that the content is copyrightprotected, a copyright protected content signal is transferred. When itis decided that information indicating the connected receiver isincluded in the held information, a non-copyright protected contentsignal is transferred regardless of whether the content is copyrightprotected. For this reason, so far as the receiver does not have afunction for enabling copying, even copyright protected content can beused.

[0195] Further, a change in connection of the connected receiver ismonitored for while transferring a content signal of copyright protectedcontent data without providing copyright protection. When a change inconnection is detected, transmission of a non-copyright protectedcontent signal is prohibited. For this reason, even if a receiver havinga function for enabling copying is switched to while content signal isbeing transmitted without providing copyright protection, the contentcan be copyright protected.

[0196] Further, since the information indicating the receiver is held ina tamper-proof updateable manner, copyright protection can be correctlyprovided to the content. Further, even if a new receiver not having afunction enabling copying is connected, it can be easily handled byupdating the information.

[0197] Further, it is possible to provide a data distribution system anda data distribution method enabling a content owner to directly controlcopying as desired while using a standard apparatus as a processor afterthe receiver.

[0198] Further, it is possible to provide a data receiver used in such acontent distribution system, receiving the distributed content data,performing adequate right processing, and outputting the content data ina usable manner.

[0199] Further, it is possible to provide a data provider and a dataproviding method for providing content data to be distributed in a statewhere the owner of the content can control the usage thereof.

[0200] Further, it is possible to provide a data transferer fortransferring the data provided in this way.

[0201] Industrial Applicability

[0202] The present invention can be applied to a music distributionsystem for distributing for example musical works via a network,hardware used for that music distribution system, and data processingmethods in that music distribution system.

1. A transmitter comprising: a transmission processing means fortransferring a content signal or processing copyright protection on acontent signal and then transferring the processed content signal and atransmission controlling means for holding information indicating areceiver which does not have a function enabling copying of content byusing the content signal or the processed content signal transferredfrom the transmission processing means and controlling output of thesignal to be transferred from the transmission processing meansaccording to whether or not information indicating the receiver which isconnected to the transmission processing means is included in the heldinformation.
 2. A transmitter as set forth in claim 1, wherein saidtransmitter comprises a protection detecting means for determining ifsaid content is copyright protected and said transmission control meanstransfers a copyright protected content signal from said transmissionprocessing means when said protection detecting means determines thatsaid content is copyright protected and transfers a non-copyrightprotected content signal regardless of the result of decision at theprotection detecting means when it is determined that informationindicating the receiver connected to said transmission processing meansis included in said held information.
 3. A transmitter as set forth inclaim 2, wherein said transfer controlling means monitors for a changein connection of the receiver connected to said transmission processingmeans while transferring a content signal of copyright protected contentwithout providing copyright protection and controls said transmissionprocessing means so as not to transfer a non-copyright protected contentsignal when it detects that the connection has been changed.
 4. Atransmitter as set forth in claim 3, wherein said transmissioncontrolling means monitors for a change in connection of said receiverby a hot plug detection function or plug and play function.
 5. Atransmitter as set forth in claim 3, wherein said transmissioncontrolling means suspends the transfer of the non-copyright protectedcontent signal or transfers a copyright protected content signal insteadof the non-copyright protected content signal so that said non-copyrightprotected content signal is not transferred.
 6. A transmitter as setforth in claim 1, wherein said transmission controlling means holdsinformation indicating said receiver in a tamper-proof updateablemanner.
 7. A signal transfer method including of the steps of holding ina transmitter information indicating receivers not having the functionof being able to receive a content signal to copy the content andcontrolling the output of the content signal or copyright protectedcontent signal at the transmitter according to whether or notinformation indicating a connected receiver is included in the heldinformation.
 8. A signal transfer method as set forth in claim 7,comprising the steps of determining whether to provide copyrightprotection for said content using said content signal and transferringsaid copyright protected content signal when determining that thecontent is copyright protected and receiving said non-copyrightprotected content signal regardless of whether said content is copyrightprotected when determining that information indicating the connectedreceiver is included in said held information.
 9. A signal transfermethod as set forth in claim 8, comprising the steps of monitoring for achange in connection of the connected receiver while transferring acontent signal of copyright protected content without providingcopyright protection and prohibiting the transfer of said non-copyrightprotected content signal when detecting that the connection has beenchanged.
 10. A signal transfer method as set forth in claim 9,comprising monitoring for a change in connection of said receiver by ahot plug detection function or plug and play function.
 11. A signaltransfer method as set forth in claim 9, comprising suspending thetransfer of the non-copyright protected content signal or transferring acopyright protected content signal instead of the non-copyrightprotected content signal so as to prohibit the transfer of saidnon-copyright protected content signal.
 12. A data distribution systemcomprising: a data providing means for adding first control informationfor controlling a usage state of the content data to the intendedcontent data and providing the result as the data to be distributed, adata transmitting means for performing predetermined second encryptionon said provided data to be distributed and transmitting the encrypteddata to be distributed, and a data receiving means for receiving saidtransmitted encrypted data to be distributed, performing decryption ofsaid second encryption, detecting said first control information fromthe decrypted data to be distributed, and controlling the output of saidcontent data based on the detected first control information.
 13. A datadistribution system as set forth in claim 12, wherein said dataproviding means superimposes said first control information aselectronic watermark information on said content data and provides thesuperimposed content data as the data to be distributed to said datatransmitting means, said data transmitting means performs thepredetermined second encryption on said provided data to be distributedand transmits the encrypted data to be distributed, and said datareceiving means receives said transmitted encrypted data to bedistributed, performs the decryption of said second encryption, detectssaid superimposed first control information from the decrypted data tobe distributed, and controls the output of said content data based onthe detected first control information.
 14. A data distribution systemas set forth in claim 13, wherein said data providing means performspredetermined first encryption on the content data with said firstcontrol information superimposed thereon as the electronic watermarkinformation and provides the encrypted data as said data to bedistributed to said data transmitting means, said data transmittingmeans performs said second encryption for said provided data to bedistributed and transmits the encrypted data to be distributed, and saiddata receiving means receives said transmitted encrypted data to bedistributed, performs the decryption of said second encryption,generates the content data with said electronic watermark informationsuperimposed thereon by performing the decryption of said firstencryption, detects said superimposed first control information from thegenerated content data, and controls the output of said content databased on the detected information.
 15. A data distribution system as setforth in claim 14, wherein said data transmitting means adds secondcontrol information for controlling a usage state of the content data tosaid provided data to be distributed, performs said second encryption onsaid data to be distributed with the second control information addedthereto, and transmits the encrypted data to be distributed, and saiddata receiving means receives said transmitted encrypted data to bedistributed, performs the decryption of said second encryption, detectssaid second control information, generates the content data with theelectronic watermark information superimposed thereon by performing thedecryption of said first encryption for said decrypted data to bedistributed, detects the first control information superimposed as saidelectronic watermark information from the generated content data, andcontrols the output of said content data based on said detected firstcontrol information and second control information.
 16. A datadistribution system as set forth in claim 12, wherein said dataproviding means adds a control descriptor indicating said first controlinformation to said content data and provides the content data with thecontrol descriptor added thereto as the data to be distributed to saiddata transmitting means, said data transmitting means performs thepredetermined second encryption for said provided data to be distributedand transmits the encrypted data to be distributed, and said datareceiving means receives said transmitted encrypted data to bedistributed, performs the decryption of said second encryption, detectssaid added first control information from the decrypted data to bedistributed, and controls the output of said content data based on thedetected first control information.
 17. A data distribution system asset forth in claim 12, wherein said data transmitting means adds secondcontrol information for controlling a usage state of the content data tosaid provided data to be distributed, performs said second encryptionfor said data to be distributed with the second control informationadded thereto, and transmits the encrypted data to be distributed, andsaid data receiving means receives said transmitted encrypted data to bedistributed, performs the decryption of said second encryption, detectssaid second information, performs the decryption of said firstencryption for said decrypted data to be distributed to generate contentdata with the control descriptor added thereto, detects the firstcontrol information added as the control descriptor from the generatedcontent data, and controls the output of said content data based on saiddetected first control information and second control information.
 18. Adata distribution system as set forth in claim 12, wherein said dataproviding means superimposes third control information for controlling ausage state of the signal when outputting said content data by an analogsignal on the content data as the electronic watermark information andprovides the content data with the third control informationsuperimposed thereon as said data to be distributed, said datatransmitting means performs the predetermined second encryption for saidprovided data to be distributed, transmits the encrypted data to bedistributed, and said data receiving means receives said transmittedencrypted data to be distributed, performs the decryption of said secondencryption, and outputs the signal with the decrypted said third controlinformation superimposed thereon as the electronic watermark informationas an analog signal output in response to a request.
 19. A datadistribution system as set forth in claim 12, wherein said datareceiving means further has a memory means for storing informationconcerning charging with respect to a usage of the content data based ona usage state of said received content data.
 20. A data distributionmethod including the steps of adding first control information forcontrolling a usage state of content data to intended content data basedon an instruction of an owner of the content data and providing theresult as the data to be distributed, performing predetermined secondencryption on said provided data to be distributed, transmitting theencrypted data to be distributed, receiving said transmitted encrypteddata to be distributed at any receiver, performing the decryption ofsaid second encryption, detecting said first control information fromthe decrypted data to be distributed, and controlling the output of saidcontent data based on the detected first control information.
 21. A datadistribution method as set forth in claim 20, comprising superimposingsaid first control information as electronic watermark information onsaid content data and providing the superimposed content data as thedata to be distributed and detecting said first control information fromthe decrypted data to be distributed by detecting said electronicwatermark information from said decrypted data to be distributed.
 22. Adata distribution method as set forth in claim 21, comprising performingpredetermined first encryption on the content data with said firstcontrol information superimposed thereon as the electronic watermarkinformation and providing the encrypted data as said data to bedistributed, performing decryption of said first encryption on the datafor which decryption of said second encryption was performed to generatecontent data with said electronic watermark information superimposedthereon, and detecting said superimposed first control information fromsaid generated content data.
 23. A data distribution method as set forthin claim 22, comprising adding second control information forcontrolling a usage state of the content data to said provided data tobe distributed, performing said second encryption on said data to bedistributed with the second control information added thereto,transmitting the encrypted data to be distributed, receiving saidtransmitted encrypted data to be distributed at any receiver, performingthe decryption of said second encryption, detecting said second controlinformation, generating the content data with the electronic watermarkinformation superimposed thereon by performing the decryption of saidfirst encryption for said decrypted data to be distributed, detectingthe first control information superimposed as said electronic watermarkinformation from the generated content data, and controlling the outputof said content data based on said detected first control informationand second control information.
 24. A data distribution method as setforth in claim 20, comprising adding said first control information byadding a control descriptor indicating said first control information tosaid content data and detecting said first control information bydetecting said added first control information from the data to bedistributed for which decryption of said second encryption is performed.25. A data distribution method as set forth in claim 24, comprisingadding second control information for controlling a usage state of thecontent data to said provided data to be distributed, performing saidsecond encryption for said data to be distributed with the secondcontrol information added thereto, transmitting the encrypted data to bedistributed, receiving said transmitted encrypted data to bedistributed, performing the decryption of said second encryption,detecting said second information, performing the decryption of saidfirst encryption for said decrypted data to be distributed to generatecontent data with the control descriptor added thereto, detecting thefirst control information added as the control descriptor from thegenerated content data, and controlling the output of said content databased on said detected first control information and second controlinformation.
 26. A data distribution method as set forth in claim 20,comprising superimposing third control information for controlling ausage state of the signal when outputting said content data by an analogsignal on the content data as the electronic watermark information andproviding the content data with the third control informationsuperimposed thereon as said data to be distributed, performing thepredetermined second encryption for said provided data to bedistributed, transmitting the encrypted data to be distributed,receiving said transmitted encrypted data to be distributed at anyreceiver, performing the decryption of said second encryption, andoutputting the signal with the decrypted said third control informationsuperimposed thereon as the electronic watermark information when atleast an analog signal output is requested.
 27. A data distributionmethod as set forth in claim 20, comprising charging for usage of thecontent data based on a usage state of said received content data.
 28. Adata receiver for receiving a signal comprised of data to be distributedincluding intended content data plus first control information forcontrolling a usage state of the content data and transmitted afterperforming predetermined second encryption, comprising a receiving meansfor receiving said transmitted signal, a second decrypting means forperforming decryption of said second encryption with respect to saidreceived signal, a first control information detecting means fordetecting said first control information from said decrypted data to bedistributed, and an output controlling means for controlling the outputof said content data based on said detected first control information.29. A data receiver as set forth in claim 28, wherein said signal to betransmitted is a signal comprised of content data plus first controlinformation on which predetermined first encryption is performed andfurther on which predetermined second encryption is performed, saidreceiver further comprises a first decrypting means for performingdecryption of said first encryption with respect to the data decryptedby said second decrypting means, and said first control informationdetecting means detects said first control information from said data tobe distributed resulting from the decryption at said first decryptingmeans.
 30. A data receiver as set forth in claim 29, wherein said firstdecrypting means performs said decryption using predetermined key datadistributed by an owner of said content data.
 31. A data receiver as setforth in claim 30, wherein said second decrypting means performs saiddecryption using predetermined key data distributed by a transmittingparty of said signal.
 32. A data receiver as set forth in claim 31,wherein said first control information is superimposed on said contentdata as electronic watermark information, and said first controlinformation detecting means detects said first control informationsuperimposed as said electronic watermark information from saiddecrypted data to be distributed.
 33. A data receiver as set forth inclaim 28, wherein said signal to be transmitted is a signal comprised ofcontent data plus said first control information and second controlinformation for controlling a usage state of said content data on whichpredetermined first encryption is performed and further predeterminedsecond encryption is performed, said receiver further comprises a secondcontrol information detecting means for detecting said second controlinformation from said decrypted data to be distributed and a controlcontent determining means for determining a content of control based onsaid detected first control information and second control information,and said output controlling means controls the output of said contentdata in accordance with the determined content of control.
 34. A datareceiver as set forth in claim 33, wherein said first controlinformation is information set by an owner of said content data, saidsecond control information is information set by a transmitting party ofsaid signal, and said control content determining means determines saidcontent of control so that the setting by the owner of said content datais given priority over the setting by the transmitting party of saidsignal based on said detected first control information and secondcontrol information.
 35. A data receiver as set forth in claim 31,wherein said first control information is added to said content data asa control descriptor, and said first control information detecting meansdetects first control information added as said control descriptor fromsaid decrypted data to be distributed.
 36. A data receiver as set forthin claim 28, wherein said signal to be transmitted is a signal comprisedof said content data plus third control information for controlling ausage state of the signal when outputting said content data by an analogsignal as the electronic watermark information, and said outputcontrolling means outputs a signal including said third controlinformation superimposed as electronic watermark information whenoutputting said content data by an analog signal in response to arequest.
 37. A data receiver as set forth in claim 28, further having amemory means for storing information concerning charging with respect toa usage of the content data based on a usage state of said receivedcontent data.
 38. A data provider comprising a control informationadding means for adding control information for controlling a usagestate of content data designated by an owner of the content data tointended content data and provides the content data with said controlinformation added thereto as data to be distributed.
 39. A data provideras set forth in claim 38, which further has an encrypting means forencrypting by a predetermined scheme the content data to which saidcontrol information is added and provides said encrypted content data.40. A data provider as set forth in claim 39, wherein said controlinformation adding means superimposes said control information on saidcontent data as electronic watermark information.
 41. A data provider asset forth in claim 39, wherein said control information adding meansadds said control information to said content data as a controldescriptor.
 42. A data provider as set forth in claim 38, which furtherhas an analog signal control information adding means for superposing,as electronic watermark information on said content data, analog signalcontrol information, designated by an owner of said content data, forcontrolling a usage state of a signal when said content data is outputas an analog signal and provides content data on which said analogsignal control information is superimposed.
 43. A data providing methodincluding the steps of adding control information for controlling ausage state of content data designated by an owner of content data tointended content data, encrypting said content data with the controlinformation added thereto by a predetermined method, and providing theencrypted content data as the data to be distributed.
 44. A dataproviding method as set forth in claim 43, including providing key datafor decrypting said encrypted content data to only a receiver receivingsaid distributed encrypted content data.
 45. A data transferercomprising an encrypting means for further encrypting, by apredetermined method, data to be distributed including intended contentdata plus control information for controlling a usage state of saidcontent data designated by an owner of the content data and encrypted bya predetermined scheme and a transferring means for transferring saidencrypted data to be distributed to any channel.